The alleged mastermind of the September 11 attacks has confessed to his role in those and other al-Qa'eda attacks, according to an edited transcript of a hearing at Guantanamo Bay released by the Pentagon late last night.

"I was responsible for the 9/11 operation, from A to Z," Khalid Sheikh Mohammed said in a statement.

"I was the operational director for Sheikh Osama bin Laden for the organising, planning, follow-up, and execution of the 9/11 operation," he said.

Mohammed, who was arrested in Rawalpindi in 2003, also allegedly acknowledged responsibility for over 30 other terror attacks or plots, including plans to bomb other landmarks in the US and the UK, including Big Ben and Heathrow airport.

Mohammed said in the statement, read for him during a closed-door military hearing at the US naval base in Guantanamo Bay, Cuba, that the attacks were part of a larger military campaign. He also indicated that earlier statements he had made to the CIA were the result of torture, but said his confession on Saturday was not made under duress.

The presiding colonel said Mohammed's allegations of torture would be "reported for any investigation that may be appropriate" and would be taken into account in considering his enemy combatant status.

Hearings are being held into 14 of the most "high-value" suspects held in Cuba. Mohammed is considered the most important of the 14, who were moved to Guantanamo Bay last year from secret CIA detention facilities overseas.

Mohammed, a Pakistani national, claimed responsibility for dozens of the worst terror plots attempted or carried out in the last 15 years, including the 2002 bombing of a nightclub in Bali, Indonesia.

In a section of the statement that was blacked out, he confessed to the beheading of Wall Street Journal reporter Daniel Pearl, according to the Associated Press. Pearl was abducted in January 2002 in Pakistan while researching a story on Islamic militancy and Mohammed has long been a suspect in the killing.

The transcript also makes clear that al-Qa'eda wanted to down a trans-Atlantic aircraft during would-be shoe bomber Richard Reid's operation.

The September 11 terror attacks killed 2,972 people, destroyed the World Trade Centre and damaged the Pentagon. Speaking through a translator, Mohammed said he was "not happy" about the victims, saying he did not like to kill people, but justified his actions as part of a holy war against the United States.

The Pentagon released the redacted transcripts of the hearing along with those of two other captured suspected al-Qa'eda operatives - Abu Faraj al-Libi and Ramzi bin Al-Shibh. The hearings, which began on Friday, are to determine whether each detainee can be deemed an "enemy combatant." Such a designation would clear the way for a criminal trial in a US military tribunal under the new military commissions law signed by President George W Bush in October.

Around 385 men are being held in the Guantanamo Bay base on suspicion of links to al-Qa'eda or the Taliban. Legal experts and journalists have criticized the US decision to bar independent observers from the hearings.